1. Field of the Invention
The present invention relates to a memory management technique and, more particularly, to a memory management technique in a graphic processor unit.
2. Description of the Related Art
With the development of computer graphics technology in recent years, image data output from information processing apparatuses like a mainframe computer, a personal computer and a game device is becoming more and more complex and advanced. In this background, these information processing apparatuses have a built-in graphic processor unit dedicated to image processing apart from a main processor for ordinary processing, in order to eliminate system overhead by releasing the main processor from image processing.
The main processor in these information processing apparatuses may process a plurality of tasks simultaneously. In association with task switching in the main processor, the graphic processor unit is also required to switch between tasks. An image memory dedicated to image processing in the graphic processor unit is limited in its size. Therefore, when the image memory is shared by a plurality of tasks, it is necessary, in switching from one task to another, to transfer image-related data stored in the image memory to a separate memory area prior to the switching before writing new image-related data in the image memory.
Rewriting of image data in the image memory requires some time. Therefore, in the case of a task in which graphics output in response to the user's operation vary in real time as in a game, the overhead associated with task switching may cause degradation in image quality such as video discontinuity or dropped frames.